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Averages are funny things. If you ask a whole bunch of people how they would rate themselves as a car driver, the overwhelming majority would confidently say they were better than average. But that's impossible. The average is the mid-point, so half of the drivers have to be better than average, while the other half have to be worse.

So some people must be unable to appraise or evaluate their own skills accurately. And that's what David Dunning and Justin Kruger found way back in 1999, with their paper entitled Unskilled and Unaware of It: How Difficulties in Recognising One's Own Incompetence Lead to Inflated Self-Assessments.

In their paper, they tell the story of the bank robber Mr McArthur Wheeler, who in 1995 in broad daylight walked into two separate banks in Pittsburgh in the USA. He wore no disguise or balaclava or mask and indeed, went out of his way to locate and smile at the surveillance cameras.

The police showed the surveillance tapes on TV, and he was arrested that night. He was flabbergasted that he had been caught, and protested: "But I wore the juice." He had been told that if he first rubbed his face with lemon juice, the cameras could not see or register his face.

And he had proved it — at least to his own high standards. He had rubbed lemon juice on his face and, holding his Polaroid camera at arm's length, had taken a photograph of his own face. Unfortunately, he had accidentally rotated the camera upwards so that he took a photo of the ceiling — but, because his face was not in the photo, he was convinced that the lemon juice had made his face invisible to cameras.

Now Mr Wheeler, the unsuccessful bank robber, was an exceptional case but we all know people who are truly incompetent, and so totally unaware of it that they actually think they are better than average. People who think they are above average include business managers, students, the per cent of university professors who think they are better than the average university professor, and of course, practically everybody who drives a car.

Back in 1999, Dunning and Kruger tested psychology students for their abilities in grammar and logic — and then they asked the students to rate themselves on how well they thought they performed. As you would expect, there was a bell curve, with most of the students performing around the middle, and smaller numbers doing really well or really badly.

Typically, the students who did badly thought they had done well. Yes, the students in the bottom 12 per cent actually estimated that they were in the top 38 per cent. Now in grammar or logic, the skills needed to provide the correct answer are the same skills you use to evaluate if the answer is correct. According to Dunning and Kruger, these students could neither give the correct answer, nor recognise when they were wrong.

The situation was different with the students who did well. They made the opposite mistake of the weaker students — they thought that they had done worse than they actually had. They reckoned that they were in the top 32 per cent, but actually were in the top 14 per cent. Dunning and Kruger put this down to the false-consensus effect. The better students thought that all the other students were as good as they were, and so they hadn't performed particularly well.

So the bottom students had a problem with how they rated themselves, while the top students had a problem with how they rated others.

Then Dunning and Kruger gave the students some training in basic logic, which did change things. Both the bottom students and top students now rated their abilities as closer to their real abilities.

But of course, whenever you deal with the human brain, you're opening a can of worms — the situation is always complicated.

Suppose you give the students different grades of tests — some easy, and some hard. When the task is easy, the top students rated their performance more accurately, but when it was hard, the bottom lot were better at rating themselves.

And as another example of 'complicated', this Dunning-Kruger effect (where the unskilled and incompetent rate themselves more highly), seems to happen only in the West, not in Asian countries.

Another study looked at how students balanced "self-interest" against "co-operation" in an artificial test, and then, how they rated themselves. In this study, 84 per cent of the students said they would help or co-operate with their fellow students — but only 61 per cent did. Again, another example of self-delusion.

Perhaps the philosopher and scientist, Bertrand Russell, got it right back in 1951, when he said: "One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision".

Comments (18)

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Richard :

29 May 2013 5:37:36pm

I appreciate the part about students. I always felt that good students are aware of what they don't know but poorer students are not. This was reinforced from my time as a student. My (now) wife and I were fellow students. She'd write one exam book and feel uncertain; I'd write several and feel reasonable. She usually scored a distinction and me a pass.

Biggus :

30 May 2013 1:45:56pm

G'day Richard - and others ....

Interesting reading and identifying with what has been written in the article by Dr Karl ( and Bertrand Russell ) ... I've always felt embarrassed or at least "uneasy" if / when someone has given me praise for achieving certain results ... as I have / HAD always assumed that just about everyone else could do "as good as I", at most, if not all, endeavors ...

BUT ...

Now that I've aged a fair bit - I have gradually come to the inexorable conclusion - that some people ARE just "too stupid to REALISE that they are, in fact - stupid !" ...( I say this now - after a lifetime of working as a Marine Captain & Engineer, a luthier ( having done major work for the likes of ACDC, Cold Chisel, INXS, Angels and a host of others ), constructing ( with the help of my lovely wife ) an aircraft - which we have flown over a huge percentage of Australia so far, and a long list of other very pleasing achievements - all done, with the expectation that "anybody else" could have done likewise ....

I do like to recall one of Alberts' ( Einsteins ) more simpler quotations - when he said : "Imagination is far more important than knowledge"

Biggus( I too am named "Richard" .... but I'm also a BIG boy - and when Life of Brian was released - my fate was sealed ! :o) )

ME :

Frogflier :

06 Jun 2013 10:53:16pm

Interesting...since there seems to be here an ignorance of the scientific fact that our planet has experienced several ice ages - all without human intervention. Additionally, the detailed data (much of it proved to be suspect by those in the scientific community with integrity) we possess only encompasses a couple hundred years at best - a drop in the chronlogical bucket and therefore statistically insignificant. It seems we have identified more individuals here that believe they are more "competent" than they really are.

Don :

Xyranius :

30 May 2013 7:36:08am

The pedant in me has to point out the opening paragraph is a fallacy confusing the mean (average) with the median (mid-point). It is possible for more than half of people to be above average. Take for example, the following list of numbers:

Ben :

The pedant in me has to point out that, statistically, mean and median are both considered forms of average, as is mode.

For instance, while most people have more than the average number of legs (mean), the average person still has two legs (median and mode).

I think it is reasonable to assume that when someone considers themselves to be an above average driver, they think they are better than most other drivers. So they are using the median, not the mean (assuming there is a difference between the two).

Dalma :

30 May 2013 2:43:59pm

Reminds me of my uppity neighbor who had tickets on her family - she vouched her husband and 10 year old were members of " MENSA ", were highly intellectual and articulate, although he was employed as a Teacher's Aide ! The moral, we can all dream, but just when do we come down to Earth ?

Bruce C :

30 May 2013 8:39:33pm

Actually the median is the midpoint of a population. It is entirely possible for the average to not equal to the median. It can be greater or less than the median depending on the skew of the distribution of the population.

Robin :

30 May 2013 10:48:00pm

One reason we all think we're above average drivers is because we have two categories of driver in our minds; other drivers and ourselves. Everytime we drive we see lots of mistakes and poor driving by 'other drivers' but might only make one mistake or do something silly occassionally, so when we compare the ratio of mistakes between others and ourselves it seems like we are better.

Enigma :

31 May 2013 12:50:47pm

When doing my Heavy Vehicle apprentiship I was appalled that a fellow student was very happy that he had scraped through an exam on braking systems with a 51 percent mark. I made the point of asking him would he want to drive a truck that had been repaired by someone that did not understand 49% of what he was working on. At a 90% pass I was uncomfortable with that potential 10% lack of knowledge on my behalf!

Samantha :

02 Jun 2013 8:53:00am

I used to know a guy that is extremely dumb and arrogant. His relatives are always saying how great he is. They would say this to his face and to strangers, building up his ego. He has a lot of confidence in approaching people and tasks. He applied for a building engineering job and got it because he showed confidence in the interview. He went straight to the bank and got a mortgage to buy a house, even through he had not started work yet. He used his parents house for collateral. After 4months he was fired because his work is faulty and the company was losing money due to his mistakes. He believes that he is smarter then his old boss; and that the boss is envious of him. I did not complete high school, yet when I looked at this guy's work I was shocked at how faulty it is. Over the past 9years he has been hired and fired 4 times. I do get worried when people are hired for important jobs that they can not do. Yet employers do choose the people that are showing confidence.